# Line Arrays - Please Educate Me

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### Line Arrays - Please Educate Me

Hello everyone and good day.

Thank you for the admin and mods for this interesting forum.

What brand/s are widely used and recognized worldwide? Any specific line?

What are the differences compared to point-source loudspeakers?

How do we know how far it can reach and cover?

My apology for the many questions.

Thank you very much.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

Hi - Welcome to the forum...!

This isn't homework-related is it...?

http://www.soundonsound.com/forum/showf ... t=1#516806

http://www.soundonsound.com/sos/mar06/a ... arrays.htm

BJG145
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### Re: Line Arrays - Please Educate Me

The second link above is a brilliant article. Should answer all you questions.

As far as brands, search for line arrays using your preferred internet search engine, and you should come up with some options.

Dave Rowles
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### Re: Line Arrays - Please Educate Me

Well, firstly we'll never be able to cover it all on here, there really is a massive amount of info on this out there.

Line arrays are many and varied, and not every set of speakers in a line is actually a line array.

One of the big principles of a line array is to remove the inverse square law for speakers (i.e., the sound no longer quarters in level for a doubling of the distance), instead it is a straight linear relationship, for this to happen the length of the array has to be a function of the lowest wavelength producible by the array, this can often mean arrays of tens of feet in length.

Also not all arrays are of the "line" type along their length, many become point sources at the bottom of the array to provide a near field (in flown arrays, called a downfill) fill.

Big manufacturers are D&B Audiotechnik, Meyer (active systems), Nexo, JBL, L'acoustics to name but a few.

Most if not all of these manufacturers have white papers etc on their websites that give a much more detailed explanation.

Reasons for use are often the distance/spl laws mentioned above, directionality (important for things like outdoor festivals where annoying the neighbours may result in you loosing your entertainment licence), on and they look cool for rock and roll.

Ian
ian_gibbs
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### Re: Line Arrays - Please Educate Me

An amazing inputs everyone, thank you very much.

What can you say about Electro-Voice or EV? I heard that Dallas Cowboys Stadium is using these.

@BJG - haha it's not homework-related bro, thanks a lot for the links.

@ian_gibbs - could you please explain further about the inverse square law not being applicable to this line array system.

Have a nice day.

Chris
pacfanttoy
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### Re: Line Arrays - Please Educate Me

In what is effectively the near field of a line array system the wavefront is cylindrical (It becomes spherical in the far field).

A Line source array can be thought of as being close to a vertical slot radiator, which has a very wide horizontal pattern and a narrow vertical one (usually with a few lobes).
This narrow vertical pattern means that over reasonable distances the line source array generates an approximation to a cylindrical wavefront as the curvature in the vertical direction is very much smaller then that in the horizontal.

The surface area of a cylinder rises linearly with increasing radius, while that of a sphere rises as the square of the radius, thus within the design limits of the system the power per unit area falls off linearly for a line source array and as the square of the distance for a point source array.

Regards, Dan.
dmills
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### Re: Line Arrays - Please Educate Me

Thank you very much Dan for your valuable inputs here.

Please feel free to post more.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

Surely if you were that interested in it, you'd research some of it yourself?
benniferj
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### Re: Line Arrays - Please Educate Me

ian_gibbs wrote:<snip
Big manufacturers are D&B Audiotechnik, Meyer (active systems), Nexo, JBL, L'acoustics to name but a few. >snip

I feel I need to mention Logic System .. Been using their stuff for a while, well worth a look. Good value, and great service.
I use the little CA10s which are a cross between a line and a point source, I'd say.

There is a ' jump on the bandwagon ' thing .. everyone needs to make line-arrays now, so be careful. In many situations, line-arrays are not the answer!

One great thing about all the discussion about arrays is the dawning awareness of directivity, dispersion and coverage. Sadly, this still does not stop installers allowing arrays to beam onto side-walls in so many venues. Look up comb-filtering...

Guy Johnson
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### Re: Line Arrays - Please Educate Me

benniferj wrote:Surely if you were that interested in it, you'd research some of it yourself?

I did bro. Please don't be too hard for me, didn't mean to sound stupid here. My apology.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

. . . Delete This User . . .
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### Re: Line Arrays - Please Educate Me

You're dead right Guy, I've heard some good stuff about the logic boxes, I just mention some that I'm more familiar with.

dmills has given a great to the point explanation of the inverse square law and how it changes with line arrays, a google will give you loads more info without cluttering the forum with physics that has already been done far clearer than I could.

Ian
ian_gibbs
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### Re: Line Arrays - Please Educate Me

Good day Ian.

pacfanttoy
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### Re: Line Arrays - Please Educate Me

Have a nice weekend.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

Sorry, been mega busy this week, feet haven't touched the ground.

Not used any of the EV array stuff but of the other stuff I've used of theirs I haven't been a fan.

Ian
ian_gibbs
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### Re: Line Arrays - Please Educate Me

Many thanks Ian for the updates.

Whenever I research online the name EV comes out as one of the better choices in line array systems, you mean Ian in reality they're (EV) not?
pacfanttoy
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### Re: Line Arrays - Please Educate Me

Ref "laws".

There seems to be considerable confusion (bit of a ding-dong in another place)as to how sound (in general terms) decays with distance.

For sure a spherical sound/light source, POWER goes as the inv' square but us humans are sensitive to pressure and my investigations tell me that this goes as 1 over r?

A definitive answer from a top bod' would be most welcome!

Dave.
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### Re: Line Arrays - Please Educate Me

ef37a wrote:Ref "laws".

There seems to be considerable confusion (bit of a ding-dong in another place)as to how sound (in general terms) decays with distance.

For sure a spherical sound/light source, POWER goes as the inv' square but us humans are sensitive to pressure and my investigations tell me that this goes as 1 over r?

A definitive answer from a top bod' would be most welcome!

Dave.

Short version you are correct. I doubt I could do a good enough job explaining the long version, so I leave the summary of it to a short quote from the Master Handbook of Acoustics...

Intensity of sound (power per unit area) is a difficult parameter to measure. Sound pressure is easily measured. As intensity is proportional to the square of sound pressure, the inverse square law (for intensity) becomes the inverse distance law (for sound pressure). In other words, sound pressure varies inversely as the first power of the distance. In Fig. 4-2, the sound-pressure level in decibels is plotted against distance. This illustrates the basis for the common and very useful expression, 6 dB per doubling of the distance that, again, applies only for a free field.

Everest, F. Alton (2000-09-22). Master Handbook of Acoustics (Kindle Locations 1933-1938). McGraw-Hill. Kindle Edition.

Obviously you can't see their image which is just a graph demonstrating this, but the key thing to remember is that Intensity is not the same as Pressure. Really this is a not uncommon misconception, and one I am guilty of spreading as I use intensity to differentiate the difference between perceived and measured quantities in terms of sound, but I don't go into the the actual difference between measure intensity and measured pressure, the former has not only the amplitude of the waveform to consider, but also the speed of the wave, the speed of the particles' movement transmitting the wave, and a few other things to consider IIRC.

The fun thing about this though is that even though one is the inverse square law, and one is the inverse distance law, in both the case of intensity and pressure you still lose 6dB per doubling of distance, but in the case of pressure that translates into 50% instead of 25% at that distance. Yea for decibels being nothing but straight ratios. Please don't ask me to try to explain all the math behind this, it is a headache and a half and I married a mathematician so that she could explain it and I didn't need to understand it, just follow it;)

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### Re: Line Arrays - Please Educate Me

I married a mathematician so that she could explain it and I didn't need to understand it, just follow it;)

On such things are solid and lasting relationships built, ladies and gentlemen. Get the important compatibility factors right and the rest will follow
turtles
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### Re: Line Arrays - Please Educate Me

turtles wrote:
I married a mathematician so that she could explain it and I didn't need to understand it, just follow it;)

On such things are solid and lasting relationships built, ladies and gentlemen. Get the important compatibility factors right and the rest will follow

HehHeh... there are several ways to take this;) Thanks though!

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### Re: Line Arrays - Please Educate Me

And then of course perceived loudness has a non linear relationship to both pressure and power!

You actually see exactly the same relationships in aerials (power flux density is square law vs electric field strength which is linear in the far field) which should be no surprise given that voltage and power have a square law relationship.

And of course all of these relationships only hold within the critical distance.

None the less for the right venue, line source arrays offer real advantages, but they are just so easy to misapply (and the results so horrible when misapplied). These are systems that need real understanding (and quite often computer modeling) to employ correctly and most of the manufacturers actually run courses on how to use their systems.

Regards, Dan.
dmills
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### Re: Line Arrays - Please Educate Me

dmills wrote:And then of course perceived loudness has a non linear relationship to both pressure and power!

Yep.

And of course all of these relationships only hold within the critical distance.

Dan's comment reminded me... it is important to keep that both inverse square and inverse distance are only approximations and do not take into account the effect of reflections and acoustics of the space. They are both intended to work in free space with no reflections etc., aka an 'ideal space' or in other words, the land of make believe and dragons. So when measuring levels you will find neither of these laws to be accurate in almost every case, but they will give a decent approximation. Of course you hit critical distance as Dan says, and all this goes out the window:)

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### Re: Line Arrays - Please Educate Me

Good Monday evening to all.

May I ask Dan, what do you mean by "misapply" when speaking of line array venue applications?

Sorry for my ignorance.

Chris
pacfanttoy
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### Re: Line Arrays - Please Educate Me

And what can you say about EV line arrays?

Our church's engineering department prefers this over L-Acoustics, JBL, Nexo, Meyer.

Just curious why.

pacfanttoy
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### Re: Line Arrays - Please Educate Me

I think the point that Dan is getting at, and certainly my view, or at least one of them, is that line arrays are seen as the cool, rock and roll option and due to the cool things they do with power and pressure then they must be the solution to every sound reinforcement problem. Actually when you look at most problems you may find that a point or distributed source system is the better option.

As has been said, badly deployed arrays are a waste of everyones time and money and most companies provide modelling software to ensure the array is doing what you want it to do, and, in some cases provide the correct array settings to actually get the system to preform as a line array. Take a look at d&b's array calc for a great example. It's free to download from their website. Also may companies won't let you use their larger systems without training, partly form a safe rigging point of view but also due to the fact that the system is an advert for the manufacturer and getting it wrong doesn't make the system look good.

Are you looking for advice for a new purchase for your church or just after some knowledge?

I've got a feeling your not getting any info on EV as (certainly where I'm based) it's not a massively common system, around me (Edinburgh and indeed most of central Scotland) it's d&b for most stuff with L'acoustics doing rock and Roll and the odd Meyer system here and there.

Ian
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### Re: Line Arrays - Please Educate Me

Thanks Seablade, nice to know I was sort of on the right track!

Having been weaned on the writings of P J Baxendall, G J King, Kelly,Ford,Self and many others, I am perhaps a bit "sensitive" about terminologies. I hate it when people refer to loudspeaker "efficiency" when they mean sensitivity. Efficiency is of course the ratio of power out to power in and as you point out, measuring sound power is very difficult...Heck, measuring the nominal One Watt test input cannot easily be done and is just specified as the root Z volts.

And as for rms bloody watts! @&^%!!!!
Oh! " I married a mathematician so that she could explain it"

Nice to know romance is not dead.

Dave.
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### Re: Line Arrays - Please Educate Me

Thank you to everyone who continuously contributing to this thread.

I appreciate it very much.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

happy holidays to everyone.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

Good day to everyone.

How do you set up the Line Array System if it is an OPEN-AIR area like a forest retreat?

What are the factors that must be avoided in this kind of set up?

Thanks for any replies.
pacfanttoy
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### Re: Line Arrays - Please Educate Me

pacfanttoy wrote:Good day to everyone.

How do you set up the Line Array System if it is an OPEN-AIR area like a forest retreat?

What are the factors that must be avoided in this kind of set up?

Thanks for any replies.

Teddy bears.

Dave.
ef37a
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